To evaluate the long-term safety and tolerability of oral dersimelagon.
1. Subjects provided written informed consent to participate. For adolescent subjects, both adolescent assent and parental consent will be provided.
2. Subjects who have completed: MT-7117-G01 (completed through Week 58 [Visit 12]) or, MT-7117-A-302 (completed through Week 58 [Visit 10]) or, MT-7117-A-301 (completed EOT - Week 104 or Week 130) according to protocol amendment 1 or 2.
3. Subjects are willing and able to travel to the study sites for all scheduled visits.
4. In the Investigator's opinion, subject can understand the nature of the study and any risks involved in participation, and is willing to cooperate and comply with the protocol restrictions and requirements (including travel).
1. History or presence of photodermatoses other than EPP or XLP.
2. Presence of clinically significant hepatobiliary disease at Screening, determined as clinically significant by the Investigator.
3. Subjects with AST, ALT, ALP ≥ 3.0 × upper limit of normal (ULN) or TB > 1.5 × ULN at Screening. The TB level of > 1.5 × ULN listed in this exclusion criteria may not be applicable to subjects with a documented medical history of Gilbert's syndrome. Please consult with the Sponsor for eligibility of subjects with elevated levels due to Gilbert's syndrome.
4. Subjects with or having a history (in the last 2 years) of excessive alcohol intake in the opinion of the Investigator.